In standard network architectures, the nodes within a domain implement interior gateway protocols and determine paths between the nodes of the domain including those gateways that enable addresses outside to the domain to be reached. Optimizing and managing this domain specific path finding and selection can be referred to as intradomain traffic engineering. Optimizing and managing path finding across multiple domains in contrast is referred to as interdomain traffic engineering.
Traffic engineering is an important problem in network management that selects paths between nodes to efficiently utilize the network resources. There are a number of traffic engineering algorithms that have been proposed and/or employed to separately or individually manage intradomain traffic engineering. Many of these traffic engineering algorithms are related to multi-protocol label switching (MPLS) based traffic engineering. These traffic engineering algorithms compute the optimal path assignment given the historical traffic matrix. Another simpler approach is to use an oblivious routing, where the path is computed based on the worst-case performance overall using a traffic matrix.
Interdomain traffic engineering is the management and selection of paths across domains. In large networks, network operators usually build a hierarchy of route reflectors to reduce the management overhead and the difficulties with configuration of large border gateway protocol (BGP) meshes. In general, route reflectors choose the best BGP routes, and advertise their client routers. The main challenge is that routers along a single path might receive different paths as their reflectors have a limited and local view. This problem is known to create inconsistency and oscillation in the configuration of forwarding tables in the networks, so operators try to only deploy a handful of route reflectors and provide a kind of consistency among them. An example is the route control platform (RCP), which is a centralized node that selects the best BGP route on behalf of all routers in an associated domain or autonomous system (AS). Then routers in the network can combine interior gateway protocol (IGP) and BGP data to build their forwarding information bases (FIBs). However, RCP does not enable differing optimization objectives and does not provide a systematic approach for interdomain TE. Existing primitives for interdomain TE include setting route attributes, AS number prepending, route aggregation and deaggregation.